Outside Temp of a vessel is 40 Deg C and Water inside it is 86 Deg C.. Why?

Thread Starter


Joined Sep 5, 2010
I was boiling water in a steel utensil.

Used Fluke's IR Gun (59 Max) to measure the temperature of Water inside AND the surface temp of vessel outside.

The boiling water read 86 Deg C whereas the outside surface temp of vessel read just 40 Deg C. Why is that?

If I touched the outside of the vessel it would 'feel' extremely hot but measurement shows just 40 Deg C. So what's going on here?

I tried changing the emissivity of the IR Gun but except for minor corrections, the outside temperature of this vessel containing boiling water always remained in the lows of 40s...!!

Most of the other things that I measured showed the temp in the right ballpark area... So what's going on with the Boiling Water System...!!

Thanks in adv and regards


Thread Starter


Joined Sep 5, 2010
I suspect the emissivity of the shiny metal is rather low.
Paint a patch of it with black paint (or even a black magic marker), and I think you will get a much closer temperature to the water in the container.
Awesome...!! Thank a lot for the right pointer...!!! It worked... :)...!!



Joined Mar 14, 2008
To make the kettle even more emissive, add a layer of carbon, such as from a candle flame against it for a few moments.
Carbon black has a very high emissivity.